1. Field of the Invention
The present invention relates to a sheet film forming roll, a sheet film casting apparatus, a fine pattern transferring apparatus and a sheet film. The present invention relates particularly to a temperature-controllable sheet film forming roll whose roll surface temperature varies from one place to another in a circumferential direction of the roll.
2. Description of the Related Art
One of such temperature-controllable sheet film forming rolls each whose roll surface temperature varies from one place to another in the roll circumferential direction includes: a fixed internal cylinder; a rotatable external cylinder disposed concentric with the internal cylinder; an annular medium passage formed by an interstice between the outer peripheral surface of the internal cylinder and the inner peripheral surface of the external cylinder; multiple partitioning members extending in the axial direction of the internal cylinder, and thereby partitioning and dividing the annular medium passage into multiple smaller medium passages arranged in the circumferential direction; multiple slit-shaped medium inlet ports drilled in the thickness portion of the internal cylinder at positions different in the circumferential direction of the internal cylinder so as to communicate respectively with the smaller medium passages, the medium inlet ports extending in the axial direction of the internal cylinder; and multiple slit-shaped medium outlet ports drilled in the thickness portion of the internal cylinder at positions different in the circumferential direction of the internal cylinder so as to communicate respectively with the smaller medium passages, the medium outlet ports extending in the axial direction of the internal cylinder.
This technology is disclosed in Japanese Patent Application Laid-Open No. 2006-256159 (Patent Document 1).
The sheet film forming roll needs to be made with a thin structure which causes the external cylinder (external barrel) to have a smaller heat capacity for the purpose of making the roll surface temperature of the sheet film forming roll clearly vary among the temperature controlling zones partitioned in the roll circumferential direction while the sheet film forming roll is rolling.
In this respect, the conventional type of sheet film forming roll can be employed in sheet film casting or the like by sheet forming film methods with no large pressing force applied to the external cylinder, including a peening forming method and an air-chamber forming method. However, the conventional type of sheet film forming roll cannot be employed to cast a sheet film using touch rolls that press a resin against the roll surface while casting the resin. Since the external cylinder is made to have a thin structure with a smaller heat capacity, the pressing of the touch rolls deforms the external cylinder, and thus hinders the resin from receiving a sufficient pressing force. As a result, no sheet film is casted correctly.
Furthermore, the conventional type of sheet film forming roll makes it difficult to appropriately set the temperatures for the respective medium passages (heating medium chambers) whose temperatures should be different from one another, because the heating medium leaks from and to the medium passages.